The present invention relates in general to semiconductors, and more particularly to charge pumps.
Integrated circuits are being designed for use in an increasing variety of portable applications. These integrated circuits often must be capable of operating from a battery that supplies less than two volts. However, many integrated circuits require higher voltages to perform circuit functions. For example, nonvolatile memory circuits made with electrically erasable, floating gate transistors are programmed with high voltage signals whose amplitudes can exceed fourteen volts.
The high voltage signals are derived from a high voltage supply generated on chip with a charge pump that pumps the battery voltage to the level of the high voltage supply. However, at low battery voltages prior art charge pumps are inefficient.
Hence, there is a need for an improved charge pump that operates efficiently at low voltages.